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Difficulty: MediumExcretion and Excretory Organs

Match each excretory structure listed in the left column with its characteristic structural feature or mode of action in the right column.

  • Flame cell (Protonephridium)Ciliated bulb structure that propels fluid through excretory canals
  • Nephridium (Metanephridium)Open ciliated funnel (nephrostome) collecting coelomic fluid
  • Malpighian tubuleBlind-ending tubule bathed in hemolymph discharging waste into the alimentary canal
  • NephronRenal unit consisting of a glomerulus for ultrafiltration and tubules for selective reabsorption

Answer

Flame cell matches the ciliated bulb structure; Nephridium matches the open ciliated funnel collecting coelomic fluid; Malpighian tubule matches the blind-ending tubule discharging waste into the alimentary canal; Nephron matches the renal unit with a glomerulus performing ultrafiltration.
Each organ is paired according to its functional morphology: flame cells rely on cilia inside closed bulbs to generate pressure gradients; nephridia open into coelomic cavities through nephrostomes; Malpighian tubules lie in hemolymph and empty into the midgut/hindgut junction; nephrons utilize high-pressure capillary beds (glomeruli) for ultrafiltration.

Step-by-Step Solution

1
Identify the defining structural feature of flatworm excretory units.
Flame cells are characterized by ciliated bulbs that drive fluid movement.
Protonephridia lack internal openings and rely on ciliated flame bulbs.
2
Distinguish between metanephridia, insect tubules, and vertebrate kidney units.
Nephridia feature nephrostomes opening into the coelom, Malpighian tubules extend into the hemocoel to empty into the gut, and nephrons utilize glomeruli for ultrafiltration.
Each animal phylum exhibits distinct structural adaptations for excretion suited to their body plan.

Key Concept

Comparative Anatomy of Excretory Structures Across Animal Taxa
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Topics

Excretion and Excretory Organs

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